Systolic and diastolic blood pressure levels for children and teenagers have risen substantially since 1988, according to a new study supported by the National Heart, Lung, and Blood Institute (NHLBI), part of the National Institutes of Health. The study links part of the rise to a concurrent increase in the prevalence of overweight and obesity.
The study — "Trends in Blood Pressure Among Children and Adolescents" — appears in the May 5, 2004 issue of The Journal of the American Medical Association (JAMA). The study was conducted by researchers at Tulane University in New Orleans, LA, and the NHLBI in Bethesda, MD.
This summer, the NHLBI and the National High Blood Pressure Education Program, which it coordinates, will release updated clinical practice guidelines on high blood pressure in children and adolescents. The guidelines, presented in summary form on May 1, 2004 at the annual meeting of the Pediatric Academic Societies (PAS) in San Francisco, include revised blood pressure tables and updated recommendations for lifestyle and drug therapies.
"The obesity-related rise in blood pressure among American children is a serious health issue," said NHLBI Acting Director Dr. Barbara Alving. "We need to take steps to reverse this trend. One key step is to give physicians tools that can help them deal with this problem, which is why we're issuing these new guidelines."
"The increases found by the JAMA study in children's average blood pressures may seem small, but they can have serious consequences," said Dr. Jeffrey Cutler, Senior Advisor, NHLBI Division of Epidemiology and Clinical Applications, and co-author of the JAMA paper. "Previously published data indicate that, for each 1- to 2-millimeter of mercury rise in their systolic blood pressure, children face a 10 percent greater risk of developing hypertension as a young adult."
High blood pressure is a major risk factor for heart disease and the chief risk factor for stroke.
The new blood pressure trends study in JAMA involved 5,582 children ages 8-17, who were part of the 1988-94 and 1999-2000 National Health and Nutrition Examination Surveys (NHANES). In both surveys, the children were about 50 percent male, 16-17 percent black, and 9-12 percent Mexican-American. The mean age for both groups was just under 13 years.
In 1988-94, the children's average systolic blood pressure was 104.6 mm Hg and their average diastolic pressure was 58.4 mm Hg. In 1999-2000, the children's average systolic pressure was 106 mm Hg and their average diastolic was 61.7 mm Hg.
In 1988-94, 11.7 percent of the children were overweight; in 1999-2000, 16.3 percent were overweight. Overweight is defined by body mass index (BMI), which is a measure of weight relative to height. Overweight children and teenagers have a BMI that falls in the 95th percentile or higher on age- and gender-specific growth charts, compiled by the Centers for Disease Control and Prevention.
The systolic and diastolic blood pressure increases between the two surveys were large and occurred for all age and race/ethnic groups, and both genders. The systolic pressure increased by 1.4 mm Hg and the diastolic by 3.3 mm Hg from 1988-94 to 1999-2000. Even after adjusting for BMI, systolic and diastolic blood pressures were 1 and 2.9 mm Hg higher, respectively, in 1999-2000, compared with 1988-94. This suggests that lifestyle factors other than overweight, such as physical activity and specific dietary nutrients, were also involved in the trends.
Further, systolic and diastolic blood pressures increased with age for all race/ethnic groups and both genders. For children ages 8-12, yearly systolic and diastolic blood pressure increases were greater for girls, compared with boys. For adolescents ages 13-17, yearly blood pressure increases were greater for boys, compared with girls.
The new clinical practice guidelines due for release this summer reflect new data from the 1999-2000 NHANES. The data have been added to the childhood blood pressure database and reexamined to develop revised normative blood pressure tables. The updated tables now include the 50th, 90th, 95th, and 99th percentiles of blood pressure by sex, age, and height.
Hypertension in youngsters is based on the range of blood pressures in healthy children. The new guidelines continue to define normal blood pressure as the systolic and diastolic blood pressures that are less than the 90th percentile for that sex, age, and height. To be consistent with the latest blood pressure guidelines for adults, the guidelines for children include a prehypertension category. Children with a systolic or diastolic pressure equal to or greater than the 90th percentile but less than the 95th percentile are considered prehypertensive. Hypertension continues to be defined as a systolic or diastolic pressure equal to or greater than the 95th percentile.
The new guidelines describe hypertension and prehypertension as significant health issues in the young due to the marked increase in the prevalence of overweight children. Overweight and high blood pressure are components of the insulin resistance syndrome, a combination of multiple risk factors for cardiovascular disease and type 2 diabetes. Therefore, the guidelines call for a comprehensive assessment of cardiovascular risk factors. The new guidelines, noting the association of high blood pressure and overweight with sleep apnea, also suggest that a history of sleeping patterns should be obtained in a child with hypertension.
Treatment for children with high blood pressure usually consists of lifestyle changes, including weight management, physical activity, and dietary changes. Drug therapy is used if needed. The revised guidelines incorporate recent research and present updated recommendations for lifestyle approaches, such as dietary changes for children and adolescents who have prehypertension as well as hypertension. Revised drug recommendations include dosage recommendations for many of the newer drugs studied in recent clinical trials.
"We want to give our children the best possible start in life," said Alving. "That means insuring they have a healthy blood pressure and weight. We need to teach them to be physically active and to follow a heart-healthy eating plan. Otherwise, we may be giving them an early start on heart disease."
To arrange an interview about this study, contact the NHLBI Communications Office at (301) 496-4236.
Tables from the new clinical practice guidelines on hypertension in children and adolescents are available at www.nhlbi.nih.gov/guidelines/hypertension/child_tbl.htm.